Efficiency of DNA Mini-Barcoding to Assess Mislabeling in Commercial
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foods Article Efficiency of DNA Mini-Barcoding to Assess Mislabeling in Commercial Fish Products in Italy: An Overview of the Last Decade Laura Filonzi, Marina Vaghi, Alessia Ardenghi, Pietro Maria Rontani, Andrea Voccia and Francesco Nonnis Marzano * Department of Chemistry, Life Sciences and Environmental Sustainability, University of Parma, Viale delle Scienze 11, 43124 Parma, Italy; laura.fi[email protected] (L.F.); [email protected] (M.V.); [email protected] (A.A.); [email protected] (P.M.R.); [email protected] (A.V.) * Correspondence: [email protected]; Tel.: +39-0521-905643 Abstract: The problem of fish traceability in processed products is still an important issue in food safety. Major attention is nowadays dedicated to consumer health and prevention of possible frauds regulated by national and international laws. For this reason, a technical approach is fundamental in revealing mislabeling at different levels. In particular, the use of genetic markers has been standardized and DNA barcoding is considered the gold-standard strategy to examine and prevent species substitution. Considering the richness of available DNA databases, it is nowadays possible to rapidly reach a reliable taxonomy at the species level. Among different approaches, an innovative method based on DNA mini barcoding has recently been proposed at an international level. Starting from this evidence, we herein illustrate an investigation dealing with the evolution of this topic in Italy over the last decade. The molecular analysis of 71 commercial fish samples based on mini-COI Citation: Filonzi, L.; Vaghi, M.; sequencing with two different primer sets reached an amplification success rate of 87.3 and 97.2%. Ardenghi, A.; Rontani, P.M.; Voccia, The investigation revealed four major frauds (5.8%) and four minor ones (5.8%). Results highlighted A.; Nonnis Marzano, F. Efficiency of a decrease in incorrect labeling in Italy from 32% to 11.6% over the last decade, although a recurrent DNA Mini-Barcoding to Assess involvement of “endangered” species sensu IUCN was still observed. Mislabeling in Commercial Fish Products in Italy: An Overview of the Last Decade. Foods 2021, 10, 1449. Keywords: food frauds; conservation; molecular genetics; mitochondrial DNA; cytochrome oxi- https://doi.org/10.3390/foods10071449 dase; biodiversity Academic Editor: Tiziana Pepe Received: 10 May 2021 1. Introduction Accepted: 15 June 2021 The consumption of seafood products has increased all over the world during the Published: 22 June 2021 last 50 years as demonstrated by data issued by the United Nations Food and Agriculture Organization (FAO) [1,2] that estimated the value of fish commerce to be over hundreds of Publisher’s Note: MDPI stays neutral billion dollars each year. Considering the importance of fish trade in the globalization era, with regard to jurisdictional claims in consistent monitoring of the production chain focusing on technological developments, published maps and institutional affil- handling, processing and distribution by global networks is, therefore, necessary [3]. iations. Nowadays, food quality and safety issues are crucial points for consumers, also considering the frequency of fish species substitutions. Basic consequences may be health problems that occur primarily through the consumption of cryptic species coming from contaminated areas or able to trigger allergy problems [4]. Despite financial fraud still being the main Copyright: © 2021 by the authors. issue [5], major attention must be dedicated to such cryptic species as those belonging to Licensee MDPI, Basel, Switzerland. the genera Pangasius, Salmo and Tilapia whose aquaculture exploitation makes them easy This article is an open access article substitutes for wild species [4]. distributed under the terms and Precautionary measures are, therefore, necessary, particularly for products that are conditions of the Creative Commons not visually recognizable at sight and are indistinguishable on a morphological basis after Attribution (CC BY) license (https:// processing. Deliberate mislabeling and replacement of high-value species with cheaper creativecommons.org/licenses/by/ ones is an Economically Motivated Adulteration (EMA) and is considered as fraud [5]. In a 4.0/). Foods 2021, 10, 1449. https://doi.org/10.3390/foods10071449 https://www.mdpi.com/journal/foods Foods 2021, 10, 1449 2 of 11 report paper published by the European Parliament in 2013, seafood was identified as the second most likely group of food to be subject to fraud, following olive oil [6]. Although the European Union labeling law (EU Regulation No. 1379/2013) [7] re- quests appropriate species traceability and labeling (scientific binomial nomenclature based on genus and species together with the common name), the identification of processed species is often difficult. Many scientists are working with innovative technologies to assess taxa identification and authenticity. Several molecular methods have been proposed to identify the correct species, from the use of single-protein or species-specific DNA sequences to modern genomic approaches. Among the wide variety of DNA methods nowadays available, the choice is mainly influenced by use simplicity and affordable costs in relation to the product value [8]. In recent years, the gold-standard strategy to examine and prevent species fraud has been DNA barcoding, a fast and cost-effective method for correct classification at a species level [9]. The original approach is based on the sequence analysis of a 650-bp mitochondrial DNA fragment. The cytochrome c oxidase I (COI) gene is the favorite sequence to act as a “barcode” to identify and delineate the animal lifeform [10]. Although the analysis of long DNA fragments is complex due to degradation along the different steps from production to analysis, most of the mtDNA-based studies have analyzed the full-length COI barcode [11,12]. Since the first applications of mitochondrial DNA barcoding [13], and then through constant methodological improvements [14], the most recent advances have led to an innovative approach based on mini-barcodes [15–17]. The methodology refers to the analysis of short DNA fragments and it can be applied in different fields of systematics (from museum collection research to forensic applications). COI mini-barcoding is, therefore, useful to assess the correct taxonomy in processed prod- ucts. This is particularly the case with commercial fish, for which the correct preservation under stable refrigerated conditions is a major issue during fishing, transportation and distribution. In addition, fish processing for preservation is the major cause of DNA degra- dation. Consequently, molecular analyses to reveal species substitution may face DNA degradation limitations and, therefore, become biased by technical questions. The possi- bility of analyzing short DNA fragments such as COI mini-barcoding seems to solve this issue. In the field of ichthyology, the application of mini-barcoding is nowadays possible thanks to the availability of specific databases accounting for millions of COI sequences. To give a general idea, BOLD database reports cover more than 24,000 barcoded species among Actinopterygii and Elasmobranchii. On the other hand, it is noteworthy to observe that data redundancy may generate confusion or technical biases due to contradictory attribution within a genus level. Starting from past experience of the application of COI and CytB barcoding, besides the use of additional markers [18], for the identification of species substitution in fish products [19], a new investigation was carried out to verify the usefulness of COI mini- barcoding as an innovative methodology to substitute for classic barcoding. The research was focused on sampling and analyzing the same taxa purchased in the same department stores to assess the evolution of cryptic species mislabeling after a decade, also considering the application of new European regulations [7]. The suitability of COI mini-barcoding and the evolution of the mislabeling issue are herein discussed, also considering some critical ecological, taxonomic and commercial aspects that have been arisen by experts based on their judgments. 2. Materials and Methods Fresh and frozen commercial fish products were acquired in 10 different department stores located in the Emilia Romagna region during 2020 and 2021. The different depart- ment stores belonged to the major brands fully distributed over the entire country, with their own national fish provider. In this way, although executed locally, the research had national coverage. Foods 2021, 10, 1449 3 of 11 A small sample of the edible tissue of approximately 50 mg was collected and fixed in absolute ethanol under refrigerated conditions. Samples were stored at −20 ◦C to be processed within one week of purchasing. A total number of 71 specimens belonging to 27 putative seawater species were analyzed. The samples dataset was prepared, listing the declared names and areas of fishing. The entire dataset is reported in Table1. It is noteworthy to observe that four samples (MB43, MB64, MB66, MB71) did not report the origin in the label either as a specific FAO fishing area or a summary geographic declared one. Table 1. Detailed description of analyzed samples and information reported in the labels (common name, declared scientific name and fishing area). “N/A” (not available) refers to lacking label information. Sample ID Geographical Origin Common Name Declared Scientific Name MB01 Southeast Atlantic Ocean